Hydrofoils for ships and like vessels

ABSTRACT

A control-surface device for use as a rudder or stabilizer fin. The devices described are of hydrofoil shape with jet discharge slots to either side of the device adjacent its distal portion. When used as a jet flap rudder, a jet of fluid is discharged from the advanced face of the rudder to assist steering. When used to provide a pair of stabilizer fins, jets of fluid are discharged from the leading faces of the fins as these are moved through the supporting fluid by a rolling motion of the ship.

United States Patent English [4 Aug. 1, 1972 [54] HYDROFOILS FOR SHIPS AND LIKE [5 6] References Cited VESSELS UNITED STATES PATENTS [72] Inventor: John Walter English, Shepperton,

E l d 3,326,296 6/1967 H1ll et al. ..l14/67 A Assignee: National Research Development 3,472,192 10/1969 Yuan ..114/66.5 H Corporauon London England Primary Examiner-Trygve M. Blix Filed! p 2, 1970 Attorney-Cameron, Kerkam and Sutton [21] Appl. No.: 74,311

[57] ABSTRACT [30] Foreign Application Priority Data A control-surface device for use as a rudder or stabil- B 47 306 69 izer fin. The devices described are of hydrofoil shape g i gg g t it i 3 4 with jet discharge slots to either side of the device adtea n am jacent its distal portion. When used as a jet flap ..114 162 114 126 rudder ajet fluid is discharged fmm the advanced ..B63h 25/12, 13636 39/06 face of the rudder assist Steering when used to 58 Field of Search..1 14/162, 126, 122, 67 A, 67 R, Provide a pair of Stabilizer fins, j of fluid are 114/6 5 H discharged from the leading faces of the fins as these are moved through the supporting fluid by a rolling motion of the ship.

5 Claims, 11 Drawing Figures P'ATENTEDAus 1 1972 SHEET 5 BF 6 CONTROL PATENTEDMIB III-I12 3.680.511

SHEET 5 [IF 6 I "H8 I HYDROFOILS FOR SHIPS AND LIKE VESSELS The e. g. relates to control-surface elements for ships or like vessels e.g., oil rigs. The invention has a particular application as a rudder or roll stabilizer fin.

It is well appreciated that many types of ship, including large tankers and bulk carriers in particular, could utilize more maneuvering effort over their complete speed range and in many situations. At zero and low speeds powered lateral thrust units are often employed for improving ship control without the assistance of tugs, while at low and high speeds a number of devices including steerable ducted propellers, directional water jets emerging from the ships bottom, and active rudders may be used. Apart from the steerable ducted propeller all these other methods of improving maneuverability rely on the installation of auxiliary equipment in addition to the main propulsion and steering system. This additional equipment is usually expensive and in most cases the amount of side force or turning effort that can be developed is limited because of the practical installation difficulties or for financial reasons.

Another problem of importance is the roll stabilization of the vessel. This is especially so in large passenger ships where the comfort of the passengers is paramount, and in large bulk carriers where the danger of shifting cargo in rough seas is ever present.

According to the present invention, there is provided a control-surface device including aperture defining means for the discharge of at least one jet of fluid to one or other side of the device.

In one embodiment, the aperture defining means are arranged for the discharge of said jet(s) of fluid at about 60 to a center-plane of the device.

Preferably said aperture defining means are located adjacent a distal portion of the device.

Conveniently, said device has one or more in-take openings for the introduction of external fluid into the device to provide said jets of fluid.

In a preferred variation said aperture defining means defines two discharge apertures symmetrically spaced one on each side of a center-plane of the device, and the device includes a common inlet passage for said fluid and a fluidic switch adapted in operation to connect said inlet passage with one or other of said discharge apertures.

The invention also includes a jet-flap stabilizer comprising the control-surface device of the present invention.

The invention further includes a jet-flap rudder comprising the control-surface element of the present invention.

According to another aspect of the invention there is provided a ship or like vessel having at least one pair of the jet-flap stabilizers of the present invention, the stabilizers of the or each said pair being arranged one on each side of the ship. In a preferred embodiment there is provided an automatic control system whereby in operation the jet(s) of fluid is/are discharged or not, as the case may be, in synchronism with a rolling motion of the vessel so as to oppose said motion. The automatic control system may be adapted to vary the momentum of the discharged fluid from a minimum or zero value when the ship is at one or other extremity of its rolling motion, to a maximum value when the ship is passing through the horizontal position.

In order that the present invention may be more fully understood, embodiments thereof will now be described by way of example with reference to the accompanying drawings of which:

FIG. 1 shows a diagrammatic vertical section of a first embodiment of the invention;

FIG. 2 shows a diagrammatic horizontal section taken along the line A--A of FIG. 1;

FIG. 3 shows a vertical section of a second embodiment of the invention;

FIG. 4 shows a vertical section of a third embodiment of the invention;

FIG. 5 shows a horizontal section of a trailing portion of a rudder in accordance with the invention;

FIG. 6 shows on an enlarged scale the trailing edge portion illustrated in FIG. 5;

FIG. 7 shows a vertical section of a fifth embodiment of the invention;

FIG. 8 shows a horizontal section taken along the line 8-3 of FIG. 7;

FIG. 9 is a side view of the end part of a vessel having a jet-flap rudder in accordance with the present invention;

FIG. 10 shows a vertical section of a vessel having a stabilizer arrangement in accordance with the present invention; and

FIG. 11 shows a side view of a variation of the embodiment shown in FIGS. 1 and 2.

In the embodiment of FIGS. 1, 2 and 9, a rudder 10 provides the control-surface device in accordance with the present invention. The rudder is mounted behind a propeller 12 at the stern of a ships hull l4 and the vertical extent of the propeller slip stream over the rudder I0 is indicated by the boundary lines I5, 16 in FIG. 1.

At its upper end, the rudder is located by a hollow bearing 17 which connects a passageway 18 in the rudder 10 with a watertight compartment 20 in the ships hull. Seals 22 prevent leakage. A conduit 24 connects compartment 20 with a pump (not shown).

The profile of the passageway 18 will best be seen from FIGS. 1 and 2 from which it is evident that the passageway flares (in a vertical plane) from a relatively narrow inlet port 118 to a pair of vertically disposed discharge slots 218, 318.

Viewed in a horizontal plane, the passageway 18 comprises a first portion 418 leading into a jet direction control chamber 518 for pneumatically (or hydraulically) controlling the discharge of fluid from the slots 218, 318 by means ofgas (or water).

As indicated diagrammatically in FIG. 2, the control chamber 518 is provided with a pair of control or blowing slots located one on each side of the rudder center line and fed by inlet pipes 25,26. These pipes which are controlled by appropriate valves (not shown) lead through the body portion of the rudder to a supply of pressurized gas or pumped water (not shown) located in the hull 14, or a supply of pumped water which could be taken from the main supply pump.

A plurality of splitter plates 30 are located in the horizontally tapering part of passageway portion 418 and are roughly equally spaced (in a vertical sense) from one another and from the top and bottom profiles of this portion (FIG. 1).

At its lower end the rudder may be supported by a stern frame sole piece 27 vertically aligned with the bearing 17 to permit pivoting of the rudder about a vertical axis X X. Movement of the rudder is effected by a stock 28. It will be appreciated that the invention is also applicable to other types of rudder e.g. an overhung rudder.

In use, the rudder of the above described embodiment may either be operated as a conventional rudder or as a jet assisted rudder depending on the prevailing circumstances. Thus where the vessel is at sea, the pump is not started and the rudder is operated in an identical fashion to one of conventional design and the same shape and size. However, where good manoeuvrabitily at low speeds is desirable, the pump may-be started to discharge water (via compartment 20, the bearing 17 and passageway 18) from one or other of the discharge slots 218, 318.

Where the rudder is inclined to the onset flow to turn the ship, the choice of slot depends on the sense of the rudder. inclination. This selection is achieved in practice by means of the control slots which are fed by pipes 25, 26. Thus when the rudder is inclined with its port surface advanced towards the onset flow, then the valve for the starboard pneumatic or pumped water control slot will beopened to deflect the fluid discharge from the passageway portion 418 to the port slot. When the rudder is inclined with its starboard surface advanced towards the onset flow, then the port valve is opened (with the starboard valve shut) to bring the starboard slot into operation.

FIG. 11 shows a modification of the above embodiment in which the rudder stock 28 is made hollow and the hollow bearing 17 of the previous embodiment is replaced by a conventional bearing 17 In the FIG. 11 modification, the control-surface element is made hollow to define a plenum chamber 18' separated from the discharge slots 218, 318 by the usual jet direction control chamber 518. Details of the control fluid lines etc. associated with chamber 518 and the operation of this chamber are illustrated in FIGS. 1 and 2 and have already been described above. These figures also show more clearly the form of the control chamber. The external profile of the rudder is identical (apart from optional dimensional changes) to that shown in the embodiment of FIGS. 1 and 2. In operation of the rudder as a jet-assisted rudder, water is pumped through the hollow rudder stock into the plenum chamber from whence it passes (under the control of chamber 518) to one or other of the discharge slots 218, 318.

It can be calculated that the power required to produce the jet is directly proportional to jet momentum and slot length, and inversely proportional to the square root of the jet thickness. In the case of a rudder using a water jet it will be desirable to supply the hydraulic power in the form of high-head and low flow rate, so that the size of the installation and equipment can be kept down and the hydraulic losses involved in transmitting the water over possibly large distances and through bends does not become too large. Also it is desirable that the characteristics of the conventional water ballast pumps should be suitable for powering the rudder jets where possible. Alternatively, it may be desirable to install a larger ballast pump than would normally be provided with a view to using it for the dual purpose of ballast and jets. Both the jet thickness and the momentum co-efficient should be kept small to satisfy the high-head and low flow rate condition, but at the same time the slot thickness cannot be made too small on practical grounds because the jet power will become too large. There are conflicting requirements coming in here, one requirement being low jet speed and a large slot for a given flow rate with low loss of kinetic energy at the outlet, the other being high jet speed and low internal losses due to the lower flow rate required. For a given system it will be possible to optimize the system as regards power once a rough idea of the system layout is known. But since the layout will vary from ship to ship it is not possible here to generalize further.

In a second embodiment of the invention (FIG. 3) the rudder is mounted similarly to that illustrated in FIG. 1 and 2 but the passageway 18 of modified profile now extends from an intake port 50 at the leading edge of the rudder to the pneumatic or water control chamber and discharge slots located adjacent the trailing edge of the rudder. The chamber 18 and slots 218, 318 etc. are essentially the same as those already described in the previous embodiment and they will not be further discussed here.

As indicated in FIG. 3, the rudder 10 houses a multielement pump 52 for pumping water from port 50 through a manifold 54 and the passageway 18 to one or other of the slots 218, 318. In this embodiment the motor 56 for the pumpis actually housed within the body portion of the rudder. Control lines for starting and stopping this motor extend upwardly from the rudder (e.g. through the bearing 17 or stock 28) into the hull of the ship.

A further embodiment (FIG. 4) of the invention differs from that of FIG. 3 in the profile of the passageway 18 and in the connections to the pump 52 which is now provided with an inlet manifold 60 in addition to the (outlet) manifold 54. Thus in this instance the prime mover for the pump drive is located in the hull of the vessel and drives the pump through co-operating bevelled gear wheels 62 in the hull 14.

Any of the embodiments of the invention described above may be modified by the replacement of the inlet ports 50 by a pair of apertures 70, 72 located one on either side of the rudder as shown in FIG. 5, which shows a modification of the FIG. 3 and FIG. 4 embodiments. Valves 74, 76 control the intake of fluid through these apertures. The valves will usually be operated so that the intake of fluid is limited to the intake aperture on the lower pressure side of the rudder (aperture in this case). Where the rudder is inclined to the onset flow in the opposite sense to that illustrated, however, the valve 74 will be closed and valve 76 opened so as again to take fluid from the lower pressure side of the rudder. It is thought that this use of an intake slot to one side of the rudder or the other also contributes towards the circulation produced by the rudder and hence towards its effectiveness.

It will be appreciated that the above described proposals in accordance with the present invention could be very attractive on both practical and economic grounds since they could provide a means of capitalizing an existing installed equipment in some cases, without the need for additional expensive auxiliary machinery. Also the extra maneuvering effort is likely to be much greater than that which could be produced with conventional powered lateral thrust units. Indeed the production of side forces on a ship by means of direct jet reaction is comparatively a very expensive proposition particularly at low speeds when the thrust that might be expected is reduced because of adverse suction pressures on the hull surface.

In the embodiment of FIGS. 7, 8 and 10 of the drawings, a pair of roll stabilizer fins 10 provide control-surface devices in accordance with the present invention. The fins are mounted so as to be symmetrically arranged one on each side of a ships hull 614 below the water-line 616.

At its innermost end, each fin 10 is located on the hull by a hollow mounting 617 which allows the connection of a passageway 18 in the fin 10 with a variable speed pump 620 in the ships hull. The pump 620-is provided with a speed control 622 which is itself controlled by a gyro unit 624 sensitive to the rolling motion of the ship.

The profile of the passageway 18 can be seen from FIGS. 7 and 8 from which it is evident (FIG. 7) that the passageway flares outwardly (in the transverse plane of the ship) from a relatively narrow inlet section 118 to a pair of horizontally disposed discharge slots 626, 627, 28, 29 extending over substantially the whole length of the fin. These slots are separated from the remainder of the passageway 18 by a directional control chamber 518. Viewed in the orthogonal plane (FIG. 8), the passageway 18 decreases in size from the inlet to the discharge ports. A plurality of splitter plates 631 are located in the vertically tapering portion 418 of the passageway 18 and these are roughly equally spaced (in the horizontal sense) from one another and from the inner and outer profiles of this portion (FIG. 7).

As indicated diagrammatically in FIGS. 8 and 10, each chamber 518 is provided with a pair of control or blowing slots 632, 633 (634, 635) located one on each side of the fin center-line. These blowing slots are connected by pipes 638 (slots 632, 635) and 639 (slots 633, 634) in the body parts of the fins to a unit 642 for the supply of control fluid. Where pressurized gas is used for the control fluid, unit 642 may be a compressor in the hull 614. Alternatively, a liquid e.g. water, may be used as the control fluid. A switch 644 controlled by the gyro unit 624 is arranged between the unit 642 and the pipes 638, 639 to connect the units output with pipes 638 or 639 as the case may be.

In use, the gyro unit 624 responds to the presence of a rolling motion in the hull 614 to actuate the switch 644 and switches the supply of pressurized gas or liquid from the unit 642 between the blowing slots 632, 635 and 633, 634 in phase with the rolling motion of the vessel. This results in the jet discharge from the fins being switched between alternate discharge ports 626, 627 (when blowing slots 632, 633 are actuated) and 628, 629 (when blowing slots 633, 634 are actuated). Thus when the ship begins to roll in a clockwise (as viewed in FIG. 10) sense, jets of water are automatically discharged from the fins 10 at ports 627, 628 to increase the motion-resisting lift at the associated surfaces of these fins thereby to improve their stabilizing effectiveness. When the hull begins to roll in the opposite sense, then jets of fluid are instead discharged from the other pair of ports with the same advantage.

At the same time, the ro unit 624 o rat s th d control 622 smoothly Fri vary the pumgiing Speed l ifie pump 620 from a maximum value when the hull is rolling through the upright position illustrated in the drawings to minimum values when the hull is at the extremities of its roll. This results in the damping moment on the hull being matched to the angular (roll) velocity of the hull with advantages which will be obvious to those skilled in the art.

In an alternative embodiment the variable speed pump, 620 is replaced by a constant speed pump (preferably one whose delivery head will not change appreciably with discharge) and the speed control 622 is replaced by a control valve which is operated by the gyro unit 624 cyclically to control the flow to discharge ports 626 629 in the same way as has been already described in relation to the illustrated embodiment. The constant speed pump 620 and control valve 622' are shown in chain lines in FIG. 12.

In variations of the jet-flap rudder and jet-flap stabilizer above described in accordance with the present invention, if desired for purposes of simplicity, the internal fairing and splitter plates 30, 631 are omitted and the internal volume of the rudder or stabilier then acts as a plenum chamber receiving fluid from the hollow bearing, stock or root portion as the case may be and delivering it via a control chamber etc. to the appropriate discharge slot.

I claim:

1. A steering system in a vessel having a hull portion, said system comprising a rudder, a pivotal connection between the rudder and the hull portion, a fluid transfer chamber in said rudder, a conduit leading to the transfer chamber for the introduction of power-jet fluid to the transfer chamber, aperture-defining means defining powerjet fluid discharge apertures in a distal portion of the rudder on each side of the rudder center plane, a bifurcated duct having a passageway leading from said chamber to said apertures, surfaces defining control fluid discharge apertures which separate adjacent portions of the transfer chamber and the discharge duct passageway, a first pump means for providing a flow of power-jet fluid through the conduit to the chamber, and a second pump means for providing flows of control fluid separately to each of the control fluid discharge apertures.

2. A system as claimed in claim 1 in which the crosssectional area presented by the transfer chamber varies smoothly from a first oblong shape at the conduit end of the transfer chamber to a narrower and longer second oblong shape at the passageway end of the transfer chamber.

3. A system as claimed in claim 2 in which the conduit leads from the hull portion of the vessel to the transfer chamber, and the first pump means is located in said hull portion.

4. A system as claimed in claim 3 in which the aperture-defining means include flow-directing surfaces inclined at about 60 to the center plane of the system.

5. A water-bome vessel having a jet-flap rudder comprising a system as claimed in claim 1. 

1. A steering system in a vessel having a hull portion, said system comprising a rudder, a pivotal connection between the rudder and the hull portion, a fluid transfer chamber in said rudder, a conduit leading to the transfer chamber for the introduction of power-jet fluid to the transfer chamber, aperture-defining means defining power-jet fluid discharge apertures in a distal portion of the rudder on each side of the rudder center plane, a bifurcated duct having a passageway leading from said chamber to said apertures, surfaces defining control fluid discharge apertures which separate adjacent portions of the transfer chamber and the discharge duct passageway, a first pump means for providing a flow of power-jet fluid through the conduit to the chamber, and a second pump means for providing flows of control fluid separately tO each of the control fluid discharge apertures.
 2. A system as claimed in claim 1 in which the cross-sectional area presented by the transfer chamber varies smoothly from a first oblong shape at the conduit end of the transfer chamber to a narrower and longer second oblong shape at the passageway end of the transfer chamber.
 3. A system as claimed in claim 2 in which the conduit leads from the hull portion of the vessel to the transfer chamber, and the first pump means is located in said hull portion.
 4. A system as claimed in claim 3 in which the aperture-defining means include flow-directing surfaces inclined at about 60* to the center plane of the system.
 5. A water-borne vessel having a jet-flap rudder comprising a system as claimed in claim
 1. 